Formats for optical analysis and methods of manufacturing the same

ABSTRACT

Formats for the optical testing of fluids are manufacturing using modular format components. The format components are constructed so that matching format components can be mated together to form a single format for optical testing. Formats may be manufactured using pin-and-hole construction so that pins on optical format components mate with holes on opposing format components. Optical read surfaces provided on optical format components oppose each other in a completed optical format to form a read area.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.60/515,337, filed on Oct. 30, 2003, which is incorporated by referencein its entirety.

FIELD OF THE INVENTION

The present invention relates generally to medical testing and morespecifically to optical analysis of fluids using an optical format.

BACKGROUND OF THE INVENTION

In recent years, various types of medical analysis have becomeincreasingly decentralized and more accessible to the patient. Thetesting of bodily fluids represents one example of thisdecentralization. Many tests that previously had to be performed at adoctor's office and perhaps even analyzed at a separate office can nowbe performed immediately and inexpensively in the comfort of a patient'shome. One example of such a test is blood glucose monitoring, which iswidely used among diabetic patients.

Optical analysis has presented itself as one convenient method foranalyzing bodily fluids. In a typical optical analysis application, acertain amount of fluid is placed in a read area adapted to allow lightto pass through the fluid or to reflect or diffuse upon contact with thefluid. The light as altered by the fluid can then be collected andanalyzed, with changes in the light indicating medically significantproperties of the fluid. Fluid may be directed to a read area using a“format,” or a platform for collecting and handling the fluid.

A problem arises in that the fluid volumes used for such analyses isvery small—typically in the range of from about 50 nl to about 250 nl,though not limited to any given volume. It is preferable to enabletesting with a small sample volume, but such a small sample volume callsfor the use of a small read area or window upon which the sample isplaced and through which light is passed for analysis. Further, thesmall sample size requires tight tolerances in the manufacture offormats for optical testing. To ensure consistent analysis from sampleto sample, it is important to minimize format-to-format variations inthe path light travels through an optical format. Any variability inoptical path length directly impacts the magnitude of a transmissionsignal. Smaller sample sizes drive the need for increased consistency informat construction. Solutions to address the problem of optical pathlength variation between manufactured formats have resulted in costlyprecision cuvettes, complex molding techniques, or long optical pathlengths to minimize the impact of path length tolerance. None of thesesolutions is ideal for high-production-volume, low cost, andlow-sample-volume systems.

One type of format uses a base member with a cover member adhesivelyconnected to the base member. In these formats, the placement ofadhesive between the cover and the base is one source of variation inoptical path length that tends to reduce the sample-to-sample precisionof testing.

There is a need for optical formats that are efficient to manufactureand easy to use, and that result in precise measurements.

SUMMARY OF THE INVENTION

According to some embodiments of the present invention, an opticalformat for sample analysis is manufactured of identical formatcomponents that snap together.

According to some embodiments of the present invention, optical formatcomponents having alignment pins and alignment holes are mated to eachother to form optical formats having very little light path variationfrom format to format.

According to some embodiments of the present invention, an opticalformat is manufactured in a continuous molding process.

According to some embodiments of the present invention, a continuousmolding process may make use of reels to result in molded optical formatcomponents attached to reels.

According to some embodiments of the present invention, optical formatcomponents having reagent chemicals applied thereto are mated withidentical optical format components without reagent chemicals to resultin a fully constructed optical format with reagent chemicals in a sampleanalysis area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an optical format component according toone embodiment of the present invention;

FIG. 2 is an isometric exploded view of an optical format according toone embodiment of the present invention;

FIG. 3 is a cross-sectional side view of an optical format according toone embodiment of the present invention;

FIG. 4 is an isometric view of an optical format component according toone embodiment of the present invention;

FIGS. 5 a and 5 b are isometric views of optical format componentsaccording to one embodiment of the present invention;

FIG. 6 is an isometric view of optical format components followingformation according to one embodiment of the present invention;

FIG. 7 is an isometric view of optical format components being joinedtogether according to one embodiment of the present invention; and

FIG. 8 is an isometric view of optical format components followingformation according to one embodiment of the present invention.

While the invention is susceptible to various modifications andalternative forms, specific embodiments are shown by way of example inthe drawings and will be described in detail herein. However, it shouldbe understood that the invention is not intended to be limited to theparticular forms disclosed. Rather, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DESCRIPTION OF SPECIFIC EMBODIMENTS

In optical testing of fluids for medical purposes, such as thetransmission or reflection spectrophotometry of blood or interstitialfluid for glucose concentration measurements, instruments and techniqueswhich reduce the complexity of the required medical devices or providefor easier interaction with the user are of great value. Turning to FIG.1, an optical format component 10 according to one embodiment of thepresent invention is shown. The optical format component 10 is capableof forming a reliable optical format, significantly increasing theproduction efficiency for optical testing instruments, and furtherincreasing ease of testing. The optical format component 10 of FIG. 1 isdesigned to be joined with another optical format component to form anoptical format. The optical format component 10 includes a read surface12 upon which a sample is deposited for analysis. An inlet surface 14extends outwardly from the read surface 12 and serves to direct samplefluid from outside an optical format toward the read surface 12. Theread surface 12 and the inlet surface 14 may be formed within a formatcavity 16. Slots 17 along the sides 18 and 19 of the optical formatcomponent 10 may ease handling and transportation of the optical formatcomponent 10.

A hole 20 in the optical format component 10 is positioned to enableconstruction of an optical format when another optical format componentis attached to the optical format component 10. A pin 22 projects fromthe inner surface 24 of the optical format component 10. According toone embodiment of the present invention, the optical format component 10forms an optical format when it is joined with an identical orsubstantially identical optical format component, which is inverted atopthe optical format component 10. According to the embodiment shown inFIG. 1, the centers of the hole 20 and the pin 22 are positioned adistance l_(b) from a rear surface 27 of the format component and adistance l_(s) from the side surfaces 25 and 29 of the format component.The pin 22 has a diameter d_(p) and the hole 20 has a diameter d_(h).According to some embodiments, the diameter d_(h) of the hole 20 and thediameter d_(p) of the pin are approximately equal to assure a tight fitbetween pins and their corresponding holes when optical formats areconstructed. Pins according to some embodiments of the present inventionmay be provided with vertical crush ribs to provide a tighterinterference fit. The number of hole/pin combinations and theirplacement on format components 10 may be changed according to thedesired size of the format components and the location of criticalfeatures of the format. It is preferred to provide enough hole/pincombinations to hold the format together for all post-assemblyoperations, such as packaging, shipping, and testing. The pin and holefeatures are not limited to cylindrical forms, but can be of manydifferent cross-sectional shapes. An exploded view of an optical formatformed when two format components are joined together is shown in FIG.2.

Turning now to FIG. 2, a first optical format component 26 is shown inthe process of being joined to a second optical format component 28 toform an optical format according to one embodiment of the presentinvention. The first optical format component 26 is provided with afirst pin 30 and a first hole 32; likewise the second optical format 28is provided with a second pin 34 and a second hole 36. To facilitateconstruction of an optical format from the first and second opticalformat components 26 and 28, it is preferred to provide the pins withrounded tips, as shown on the second pin 34.

To form an optical format according to one embodiment of the presentinvention, the first and second optical format components 26 and 28 aremoved together in the direction shown by arrow “A” of FIG. 2. Thus, thefirst pin 30 is inserted into the second hole 36 and the second pin 34is inserted into the first hole 32. A first read surface 38 and a secondread surface 40 are separated from each other when the optical format isconstructed to form a read area, where a sample is held during testing.According to one embodiment of the present invention, the first opticalformat component 26 and the second optical format component 28 are madeof optically clear or substantially optically clear material. In thisembodiment, a first optical window 42 (whose position is shown by thedotted line) provided on the lower surface of the first optical formatcomponent 26 of FIG. 2, and a second optical window 44 allow light topass through the read area for optical testing of a sample within theread area 48 (shown in FIG. 3). As shown in FIG. 2, the area of a firstinner surface 49 of the first optical format component 26 is large incomparison to the area of the first read surface 38. Likewise, the areaof a second inner surface 51 of the second optical format component 28is large in comparison to the area of the second read surface 40. Thewidth w of the read area 48 is governed by the height difference betweenthe first inner surface 49 and the first read surface 38 and further bythe height difference between the second inner surface 51 and the secondread surface 40. When the first and second inner surfaces 49 and 51 abuteach other, as shown in FIG. 3, a stable formation results in aninterface between the two surfaces, reducing variations in the width wof the read area 48 from one optical format to another when many opticalformats are produced. According to some embodiments of the presentinvention, the interface between the first and second inner surfaces isfree of connecting materials or connecting areas such as adhesives,sonic welding ribs, or other features that could potentially change thedimensions and tolerances of the capillary gap and optical read path ofthe format.

Turning now to FIG. 3, a cross-sectional side view of an assembledoptical format 46 according to one embodiment of the present inventionis shown. The read area 48 may comprise a capillary gap holding thesample within the read area. A fill capillary gap 50 may be formed by afirst inlet surface 52 and a second inlet surface 54.

According to one embodiment of the present invention, the first opticalformat component 26 and the second optical format component 28 areidentical or substantially identical. The first and second opticalformat components may be held together by friction between the pins 30and 34 and the holes 36 and 32. Additional or alternative connectiontechniques may be used to hold the pins and holes together. According tosome embodiments, the pins 30 and 34 are sonically welded into the holes36 and 32. Additionally or alternatively, the pins 30 and 34 and theholes 36 and 32 may be joined by adhesive at the pin-hole matinginterface. It is preferred to assure that adhesive does not attach tothe inner surfaces of the optical format components, as adhesive onthese inner surfaces adversely affects the uniformity of optical pathlength in the construction of optical formats.

It is to be understood that more than two pin-and-hole connections couldbe used to construct optical formats according to the present invention,as may be beneficial in certain applications of the present invention.For example, FIG. 4 shows an optical format component 56 according toone embodiment of the present invention featuring first and second pins58 and 60 and first and second holes 62 and 64. A multiple-pin opticalformat component may be useful when a longer optical format component isdesirable. For example, the longer optical format 56 of FIG. 4 is easierfor a user to handle than a shorter optical component.

Optical formats according to some embodiments of the present inventionmay be manufactured using different types of optical format components.For example, rather than joining identical or substantially identicaloptical format components as shown in FIG. 2, an optical format may beformed by a base component having pins and no holes, and a lid memberhaving holes and no pins. FIG. 5 a shows one embodiment of a lidcomponent 66 having first and second holes 68 and 70 adapted to matewith first and second pins 69 and 71 on a base component 73, as shown inFIG. 5 b. Lid and base components such as the lid component 66 and basecomponent 73 may be formed by molding or by punching from clear plasticstock.

Optical format components and optical formats according to the presentinvention may be manufactured using a number of manufacturing techniquesand may be constructed of a variety of materials. Optical formatcomponents may be molded, embossed, coined, or manufactured using acombination of these processes, and may be constructed of materials suchas acrylic, polycarbonate, and polyester.

Turning now to FIG. 6, a strip 70 of optical format components 72 isshown. The strip 70 has been formed by a continuous molding processemploying first and second ribbons 74 and 76. Each of the optical formatcomponents 72 has been molded on the first and second ribbons 74 and 76and these ribbons hold the optical format components in place. Slots 78provided on the optical format components 72 are the result of removingthe format in a post-molding operation. The slots have value foralignment of the format during processes such as packaging and insertingthe format into a final diagnostic meter. Molding of the optical formatcomponents 72 may be accomplished by multi-cavity injection-molding, bywhich several optical format components 72 are molded at once. Opticalformat components 72 made by this process are held in one orientationuntil the components are removed from the ribbons 74 and 76. Accordingto one embodiment of the molding process, the ribbons 74 and 76 are madeof Mylar™ and are provided with guide holes 80 for advancement along aproduction machine and slits 82 to allow easy removal of molded opticalformat components 72.

Following molding of the optical format components 72, chemical reagentsas required in particular embodiments of optical formats according tothe present invention may be applied to read surfaces 12 of the opticalformat components. Following deposition of the reagent, the reagent maybe dried. Optical format components with reagent applied to readsurfaces may next be mated with optical format components with orwithout reagent applied to their read surfaces, as shown in FIG. 7.

FIG. 7 shows a first strip 86 of optical format components being joinedto a second strip 88 of optical format components. Either the firststrip 86, the second strip 88, neither strip, or both strips of opticalformat components may be provided with reagent on their read surfaces12. In the embodiment shown in FIG. 7, the first and second strips 86and 88 of optical format components have substantially identical shapes,such that as the strips are moved in the direction shown by arrow “B,”and approach each other, the optical format components will jointogether to result in optical formats. The optical format components maybe sonically welded or connected via adhesives at the pin-holeinterfaces at this point. Joined optical formats may be left on thestrips to dispense as needed, or may be picked off the strips and placedinto containers or wrapped individually.

Alternative manufacturing processes may be used to manufacture opticalformat components according to some embodiments of the presentinvention. For example, FIG. 8 shows a two-component chain 90 of opticalformat components 92. In this embodiment of the present invention, theoptical format components 92 are joined to each other by links 94.Chains 90 of optical format components may be molded, reeled, and joinedtogether similarly to the process described above with respect to FIG.7, including the deposition of reagent chemicals on the optical formatcomponents. Similarly to the process shown in FIG. 7, optical formatsformed as chains may be packaged in strips of several optical formats,wrapped and sold individually, or separated after formation and sold incontainers holding multiple optical formats.

According to one embodiment of the present invention, optical formatcomponents are formed of optically clear or substantially opticallyclear materials. When two optical format components, such as the firstand second optical format components 26 and 28 of FIGS. 2 and 3, aremolded of optically clear or substantially optically clear materials,light may pass directly through an optical format through opticalwindows and through the sample. Alternatively, a first optical formatcomponent may be clear and a second optical format component may beopaque. Such a construction may be used in measurements based on lightreflectance or diffusion rather than light transmission.

Optical formats according to the present invention may be packaged andsold as individual optical formats or packaged and sold as multipleformats on format strips.

While the present invention has been described with reference to one ormore particular embodiments, those skilled in the art will recognizethat many changes may be made thereto without departing from the spiritand scope of the present invention. For example, while the presentinvention has been generally described as directed to medicalapplications it is to be understood that any optical fluid testingapplications might employ the principles of the invention. Each of theseembodiments and obvious variations thereof is contemplated as fallingwithin the spirit and scope of the claimed invention, which is set forthin the following claims.

1. A format for the optical analysis of a sample, said formatcomprising: a first format component having at least one first formatcomponent pin, at least one first format component hole, a first inletsurface, and a first read surface; and a second format component havingat least one second format component pin, at least one second formatcomponent hole, a second inlet surface, and a second read surface, saidat least one first format component pin being inserted into said atleast one second format component hole and said at least one secondformat component pin being inserted into said at least one first formatcomponent hole such that said first read surface and said second readsurface align to form a read area and said first inlet surface and saidsecond inlet surface align to form a fill capillary gap, wherein saidfirst format component comprises a first format component inner surfaceand said second format component comprises a second format componentinner surface, said at least one first format component pin and said atleast one second format component hole meeting at least one firstpin-hole meeting interface and said at least one second format componentpin and said at least one first format component hole meeting at leastone second pin-hole meeting interface, each of said first and secondpin-hole interfaces being joined with adhesive, with substantially noadhesive being provided between said first format component innersurface and said second format component inner surface.
 2. A format forthe optical analysis of a sample, said format comprising: a first formatcomponent having at least one first format component pin, at least onefirst format component hole, a first inlet surface, and a first readsurface; and a second format component having at least one second formatcomponent pin, at least one second format component hole, a second inletsurface, and a second read surface, said at least one first formatcomponent pin being inserted into said at least one second formatcomponent hole and said at least one second format component pin beinginserted into said at least one first format component hole such thatsaid first read surface and said second read surface align to form aread area and said first inlet surface and said second inlet surfacealign to form a fill capillary gap, wherein said first format componentcomprises first and second slots disposed on first and second sidesurfaces of said first format component.
 3. The format of claim 2wherein said second format component comprises third and fourth slotsdisposed on third and fourth side surfaces of said second formatcomponent.
 4. A method of forming a format for the optical analysis of asample, said method comprising: forming a first format componentcomprising a first format component pin, a first format component hole,a first inlet surface, and a first read surface; forming a second formatcomponent comprising a second format component pin, a second formatcomponent hole a second inlet surface, and a second read surface;aligning said first and second format components such that said firstinlet surface is approximately aligned with said second inlet surface toform a fill capillary gap and said first read surface is approximatelyaligned with said second read surface; inserting said first formatcomponent pin into said second format component hole; inserting saidsecond format component pin into said first format component hole; andapplying adhesive to at least one of said first format component pin,said first format component hole, said second format component pin andsaid second format component hole.
 5. A method of forming a format forthe optical analysis of a sample, said method comprising: forming afirst format component comprising a first format component pin, a firstformat component hole, a first inlet surface, and a first read surface;forming a second format component comprising a second format componentpin, a second format component hole a second inlet surface, and a secondread surface; aligning said first and second format components such thatsaid first inlet surface is approximately aligned with said second inletsurface to form a fill capillary gap and said first read surface isapproximately aligned with said second read surface; inserting saidfirst format component pin into said second format component hole; andinserting said second format component pin into said first formatcomponent hole, wherein at least one of forming said first formatcomponent and forming said second format component comprises moldingslots into said at least one component and molding the format componentbetween first and second ribbons.
 6. A method of forming a format forthe optical analysis of a sample, said method comprising: forming afirst format component comprising a first format component pin, a firstformat component hole, a first inlet surface, and a first read surface;forming a second format component comprising a second format componentpin, a second format component hole a second inlet surface, and a secondread surface; aligning said first and second format components such thatsaid first inlet surface is approximately aligned with said second inletsurface to form a fill capillary gap and said first read surface isapproximately aligned with said second read surface; inserting saidfirst format component pin into said second format component hole; andinserting said second format component pin into said first formatcomponent hole wherein at least one of forming said first formatcomponent and said second format component comprises forming saidcomponent as part of a chain of format components.
 7. A format for theoptical analysis of a sample, said format comprising: a first formatcomponent having at least one first format component pin, a first formatcomponent inner surface, a first inlet surface, and a first readsurface; and a second format component having at least one second formatcomponent hole, a second format component inner surface, a second inletsurface, and a second read surface; wherein said first format componentcomprises first and second slots disposed on first and second sidesurfaces of said first format component, said first format component pinis inserted into said second format component hole, said first formatcomponent inner surface and said second format component inner surfaceabut at an inner surface interface, said second inlet surface and saidfirst inlet surface align to form a fill capillary gap, and said firstread surface and said second read surface align to form a read area. 8.The format of claim 7 wherein said second format component comprisesthird and fourth slots disposed on third and fourth side surfaces ofsaid second format component.
 9. A format for the optical analysis of asample comprising: a first format component having at least one firstformat component pin, a first format component inner surface, a firstinlet surface, and a first read surface; and a second format componenthaving at least one second format component hole, a second formatcomponent inner surface, a second inlet surface, and a second readsurface; wherein said first format component pin is inserted into saidsecond format component hole, said first format component inner surfaceand said second format component inner surface abut at an inner surfaceinterface, said second inlet surface and said first inlet surface alignto form a fill capillary gap, said first read surface and said secondread surface align to form a read area, and said at least one firstformat component pin is adhesively attached to said at least one secondformat component hole.